I have a cat with an osteosarcoma on his left foot and basically it's just a matter of time before I'll need to euthanize him. I've been giving him tuna every day because he loves it and still has an appetite. It is only one meal of the day. I have two other cats and I can't give tuna just to him without them getting some so I give them a little. They are 17 and 9 years old and the 17 year old has CRF.